Hospital wheelchair intelligent positioning and monitoring system and method based on passive UHF RFID

Abstract

This invention discloses a hospital wheelchair intelligent positioning and monitoring system and method based on passive UHF RFID. The system includes a passive UHF RFID anti-metal tag module, a reader network module, a data transmission module, a positioning server module, and a monitoring terminal module. The tags have no built-in battery, require no maintenance, and are affixed to the metal parts of the wheelchair. The readers are divided into three types: parking area monitoring, area positioning, and entrance / exit boundary, respectively realizing in-situ detection, area positioning, and electronic fence functions. The positioning server calculates the location and determines the status using an area-channel composite positioning algorithm. The monitoring terminal uses a layered electronic map to achieve real-time display, scheduling, alarm, and trajectory playback. This invention enables wheelchairs to be pushed and moved around without any contact, and achieves accurate area positioning, automatic inventory, overstay reminders, and boundary crossing prevention in the complex environment of multi-story and multi-metal buildings in hospitals. It has the advantages of low cost, maintenance-free operation, strong anti-interference, and convenient deployment.

Description

Technical Field

[0001] This invention relates to the field of medical Internet of Things (IoT) technology, and more specifically to a passive ultra-high frequency radio frequency identification (UHF RFID) intelligent positioning and monitoring system and method for hospital wheelchairs. Background Technology

[0002] Hospital wheelchairs, as basic mobile nursing equipment, are currently managed primarily through manual registration, regular inspections, and manual inventory, which has significant drawbacks: 1. Low wheelchair search efficiency, causing patients and their families to search extensively and delaying medical treatment; 2. Uneven resource distribution, with localized accumulation and no wheelchairs available in key areas; 3. Manual inventory is time-consuming, labor-intensive, error-prone, and costly to manage; 4. Lack of effective monitoring, making wheelchairs susceptible to being mistakenly pushed or taken out of the hospital, resulting in serious asset loss. Existing shared wheelchairs use a QR code rental model, but this presents challenges for elderly patients and critically ill patients who lack mobile phones, are unfamiliar with the operation, or have the equipment out of power. The long unlocking time and reliance on user intervention fail to meet the immediate needs of emergency patients. Some hospitals use positioning technologies such as active RFID and Bluetooth, which have the following problems: 1. Active RFID tags require built-in batteries, are easily corroded by disinfectants, need to be replaced regularly, have limited battery life, are prone to positioning interruptions, and have high long-term maintenance costs; 2. General passive RFID positioning solutions are not optimized for the complex environment of hospitals with multi-story buildings, multiple obstructions, and multiple metals, are prone to missed reads and misreads, and are not linked with nurse station terminals, making real-time scheduling impossible; 3. Among existing related patented technologies, positioning solutions based on vision / LiDAR SLAM are costly and greatly affected by light; RFID-based wheelchair monitoring solutions for nursing homes focus on user behavior safety, rely on vision, have privacy risks, are complex to deploy, cannot achieve seamless borrowing and returning, and are not suitable for large-scale wheelchair management in hospitals.

[0003] Therefore, the industry urgently needs an integrated management system that requires zero operation, has zero barriers to entry, is fully automated, low-cost, and maintenance-free, can adapt to the environment of hospital metal interference and multipath propagation, and can realize real-time wheelchair positioning, status monitoring, intelligent scheduling, and anti-theft alarm. Summary of the Invention

[0004] The purpose of this invention is to provide a hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID to overcome the shortcomings of existing technologies. This system enables wheelchairs to be used without human contact, with accurate real-time positioning, status monitoring, loitering reminders, and anti-theft alarm functions. It has the advantages of low cost, maintenance-free tags, long identification distance, adaptability to hospital environments, and batch reading capability.

[0005] Another objective of this invention is to provide a method for intelligent positioning and monitoring of hospital wheelchairs based on passive UHF RFID.

[0006] The present invention achieves the above objectives by adopting the following technical solution: a hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID, characterized in that it includes a wheelchair identification tag module, a reader network module, a data transmission module, a positioning server, and a monitoring terminal module;

[0007] The wheelchair identification tag module uses a passive UHF RFID anti-metal electronic tag, has no built-in battery, has a unique EPC code, and is installed on the unshielded part of the wheelchair's metal frame.

[0008] The reader network module includes parking area monitoring readers, area positioning readers, and entrance / exit boundary readers, which respectively realize the functions of on-site monitoring, area positioning, and entrance / exit electronic fence. The parking area monitoring readers are set up in the outpatient hall and designated wheelchair parking areas on each floor to monitor on-site / off-site status in real time. When the signal disappears, it is reported as off-site, and when the signal is stable and exceeds the threshold, it is reported as on-site. The area positioning readers are deployed at corridor intersections, escalator entrances, elevator lobbies, and near nurse stations. The entrance / exit boundary readers are deployed at the outpatient gate, underground parking garage, emergency room, and fire exits to form an electronic fence.

[0009] The positioning server includes a database and status management, composite positioning, and trajectory analysis algorithms to realize wheelchair status recognition, location calculation, event triggering, and data storage; the data transmission module includes an Ethernet switch, a fiber optic transceiver, and a wireless AP, and the reader connects to the hospital's intranet via a Category 6 network cable / Wi-Fi, and the data is uploaded to the positioning server in real time.

[0010] The monitoring terminal module is based on the hospital's hierarchical electronic map, enabling real-time display of wheelchairs, status monitoring, alarm prompts, and trajectory playback.

[0011] As a further explanation of the above solution, the parking area monitoring reader is a low-power near-field reader with a coverage radius of 1-2 meters, used to identify whether the wheelchair is in place or out of place; when the wheelchair is pushed away, the disappearance of the tag signal indicates that it has been borrowed, and when it is returned, the stable signal exceeding the threshold indicates that it has been returned, without the need for user operation.

[0012] Furthermore, the area positioning reader is a high-power far-field reader, enabling area positioning within a floor and floor transition detection.

[0013] Furthermore, the entrance and exit boundary reader uses a directional narrow beam antenna to form an electronic fence, determine the direction of wheelchair entry and exit, and trigger a boundary crossing alarm.

[0014] Furthermore, the positioning server adopts a region-channel composite positioning algorithm, combined with RSSI or fingerprint database, to resist metal and multipath interference; the monitoring terminal supports one-key point, heat map analysis, and historical trajectory playback; the tags comply with ISO18000-6C standard and operate in the 840MHz-960MHz frequency band.

[0015] A method for intelligent positioning and monitoring of hospital wheelchairs based on passive UHF RFID, characterized by comprising the following steps:

[0016] A. System initialization, binding tags to wheelchairs, readers to locations;

[0017] B. Wheelchair borrowing detection: The wheelchair is determined to be borrowed when the signal in the parking area disappears, and the status is set to "in use".

[0018] C. In-hospital mobile positioning, area reader collects data, and calculates the floor and area location;

[0019] D. Floor transition detection: Elevator lobby recognition enables floor transition detection;

[0020] E. Wheelchair return detection: If the signal in the parking area is stable and exceeds the threshold, the wheelchair is determined to be returned and the status is set to standby.

[0021] F. The entrance / exit identifies the direction of exit and triggers a boundary crossing alarm.

[0022] In step A, the tag IDs, asset numbers, deployment dates, and other information of all wheelchairs are entered into the positioning server to establish a one-to-one correspondence; readers are deployed and the network is configured to associate the device IDs of each reader with their deployment locations (floors, areas) to create a hierarchical electronic map of the hospital.

[0023] In step B, when the patient pushes the wheelchair directly from the parking area, the parking area monitoring reader detects that the wheelchair tag signal changes from strong to weak until it disappears; the reader uploads the signal disappearance event (including tag ID, reader ID, and timestamp) to the positioning server through the data transmission module; the status management module in the positioning server updates the wheelchair status from standby to in use and records the retrieval time and retrieval area.

[0024] In step C, as the wheelchair moves within the hospital, the area positioning readers on each floor periodically read the tag, obtain the tag ID, RSSI value, and timestamp, and upload them. The positioning server estimates the current floor and approximate area of ​​the wheelchair based on the reader ID and RSSI value of the same tag data received, combined with pre-stored area information. The monitoring terminal module updates the wheelchair's icon position on the electronic map in real time and displays its current status.

[0025] In step D, when a wheelchair enters the elevator or passes through an escalator, the area positioning reader in the elevator lobby reads the tag; if the same wheelchair tag is captured by readers on different floors in a short period of time, it is determined that a floor transfer has occurred; the positioning server updates the floor attribute of the wheelchair, and the monitoring map automatically switches to the corresponding floor and displays the wheelchair's location.

[0026] In step E, when the wheelchair is pushed back to any parking area, the parking area monitoring reader detects that the wheelchair tag signal reappears and remains stable. If the signal remains stable for more than the preset static threshold T, it is determined to be returned. The positioning server updates the wheelchair status to standby, records the return time and return area, and the wheelchair icon on the monitoring terminal is restored to the standby status indicator.

[0027] In step F, when the wheelchair is pushed to the hospital entrance / exit, the directional antenna of the entrance / exit boundary reader captures the wheelchair tag; the system determines the direction of movement based on the antenna orientation and the sequence of signal changes. If the movement is going out, an out-of-bounds alarm is triggered; the positioning server generates an out-of-bounds event and displays the wheelchair ID, exit location, and out-of-bounds time in a pop-up window on the monitoring terminal. At the same time, it can link with the real-time footage from nearby cameras to remind management personnel to handle the situation promptly.

[0028] The beneficial effects that can be achieved by adopting the above-mentioned technical solution in this invention are:

[0029] 1. This invention uses passive UHF RFID anti-metal tags, which do not require battery power and directly obtain energy from the reader's radio frequency field. The lifespan is synchronized with that of the wheelchair, completely avoiding problems such as battery corrosion, periodic replacement, and positioning interruption. With the help of a three-level reader network, it can support the unified deployment of hundreds of wheelchairs, achieving zero consumables and zero maintenance throughout the entire life cycle, significantly reducing the long-term operation and maintenance costs of hospitals.

[0030] 2. This invention adopts a parking area monitoring reader structure to achieve seamless borrowing and returning and automatic status recognition. Relying on a low-power near-field parking area reader to detect the tag's presence / absence status in real time, patients do not need to scan codes, register, or touch the lock. They can simply push the wheelchair away and return it immediately. The system automatically completes the borrowing / returning judgment and status switching, eliminating the barriers to use for elderly and emergency patients and adapting to hospital emergency scenarios. At the same time, it supports returning the wheelchair to any designated parking area, greatly improving the efficiency of wheelchair turnover.

[0031] 3. This invention uses a regional positioning reader and a composite positioning algorithm to achieve accurate positioning in complex environments. By using a high-power far-field regional positioning reader to cover key nodes such as corridors, elevator lobbies, and escalator entrances, and combining a regional-channel composite positioning algorithm with RSSI fingerprint calibration, it can accurately identify the building, floor, and specific area where the wheelchair is located. It effectively overcomes interference from metal wheelchairs, medical equipment, and multipath occlusion in hospitals, and achieves stable positioning at the floor level and regional level, which facilitates one-click dispatching and nearby vehicle dispatching at the nurse station.

[0032] 4. This invention adopts an entrance / exit boundary reader + directional antenna structure to construct a closed-loop anti-theft electronic fence. The entrance / exit boundary reader + narrow beam directional antenna form an electronic fence for the entire hospital entrance and exit, which can accurately determine the direction of wheelchair entry and exit. Once the outbound behavior is detected, the boundary crossing alarm is immediately triggered, and the wheelchair ID, location, and movement trajectory are simultaneously pushed to the monitoring terminal. From the hardware structure, the unauthorized pushing of wheelchairs out of the hospital is eliminated, the entire process of asset control is realized, and the risk of loss is reduced.

[0033] 5. This invention adopts a hierarchical electronic map monitoring terminal structure, which greatly improves management efficiency. The monitoring terminal is equipped with a multi-level electronic map of the hospital, which can display the location of wheelchairs in real time, their standby / use / outbound status, and supports one-keyboard point-and-click, heat map analysis, and historical trajectory playback. It can shorten the traditional manual inventory to within 1 minute, freeing up nursing manpower and providing data support for wheelchair deployment and scheduling optimization.

[0034] 6. This invention adopts low-power intermittent scanning + anti-metal tag to meet the safety and stability requirements of hospitals. The reader adopts a low-power intermittent scanning mode with low electromagnetic radiation, which complies with the electromagnetic compatibility standards of medical equipment. With the help of anti-metal tag and phase difference calibration, it maintains a high reading rate and low false judgment rate in hospital scenarios with multiple obstructions and multiple metals, and the system operates stably for a long time.

[0035] 7. This invention adopts a generalized hardware architecture, which supports the extended management of mobile medical assets throughout the hospital. The overall architecture of the system's tags, readers, algorithms, and terminals is not limited to wheelchairs and can be directly reused for the positioning and monitoring of mobile medical equipment such as hospital beds, stretchers, infusion pumps, and ventilators. One system can meet the mobile asset management needs of the entire hospital, with strong scalability and a high return on investment. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the connection structure of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the working principle of the present invention.

[0038] Explanation of reference numerals in the attached diagram: 1. Wheelchair identification tag module; 2. Reader network module; 2-1. Parking area monitoring reader; 2-2. Area positioning reader; 2-3. Entrance / exit boundary reader; 3. Data transmission module; 4. Positioning server; 5. Monitoring terminal module; 5-1. Nurse station; 5-2. PC workstation; 5-3. Mobile terminal. Detailed Implementation

[0039] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "at least" means one or more, unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] In this invention, unless otherwise specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "below," and "over" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Above," "below," and "below" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings, making the technical solution and beneficial effects of the present invention clearer and more explicit. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0044] like Figures 1-2As shown, this invention is a hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID, including a wheelchair identification tag module 1, a reader / writer network module 2, a data transmission module 3, a positioning server 4, and a monitoring terminal module 5. The wheelchair identification tag module 1 uses a passive UHF RFID anti-metal electronic tag, conforming to the ISO 18000-6C standard, with an operating frequency band of 840MHz-960MHz. Each tag has a unique EPC code and is affixed / embedded in an unshielded location on the wheelchair's metal frame (such as the crossbeam under the seat cushion or inside the plastic backrest). The tag requires no battery, is powered by receiving radio frequency energy from the reader / writer, and has a lifespan consistent with the wheelchair itself, achieving zero maintenance.

[0045] The reader network module 2 consists of fixed UHF RFID readers and antennas deployed on each floor of the hospital. Based on their functions, they are divided into parking area monitoring readers 2-1, area positioning readers 2-2, and entrance / exit boundary readers 2-3.

[0046] Parking area monitoring reader 2-1:

[0047] Deployment locations: Designated wheelchair parking areas in the outpatient hall, on all floors of the outpatient department, and on all floors of the inpatient department.

[0048] Hardware configuration: Uses a low-power near-field reader (e.g., 15dBm transmit power), connected to a near-field antenna, with a coverage radius of 1-2 meters.

[0049] Functional configuration: Continuous low-power scanning to monitor the "in-place / out-place" status of wheelchairs within the parking area in real time. An "out-place" event is reported when the tag signal disappears; an "in-place" event is reported when the tag signal remains stable for more than a preset threshold.

[0050] Area positioning reader 2-2:

[0051] Deployment locations: key path nodes such as corridor intersections, escalator entrances, elevator lobby entrances, and near nurse stations on all floors of the outpatient and inpatient departments.

[0052] Hardware configuration: High-power far-field reader (e.g., 30dBm transmit power) is used, connected to a circularly polarized antenna, with a coverage radius of 5-10 meters.

[0053] Functional configuration: Periodically scan wheelchair tags within the coverage area, read tag ID, signal strength (RSSI) and timestamp, and upload the data to the positioning server.

[0054] Entrance / exit boundary reader 2-3:

[0055] Deployment location: Above or to the side of the door frames of the hospital's main entrances and exits (outpatient gate, underground parking garage passage, emergency passage, fire exit), forming an electronic fence.

[0056] Hardware configuration: A directional narrow beam antenna (e.g., an 8dBi flat panel antenna) is used, with a beamwidth ≤60° to ensure accurate identification only in the direction of entry and exit.

[0057] Functional configuration: Real-time monitoring of the moment a wheelchair passes through an entrance or exit, determining the direction of movement (entering / exiting) based on the antenna orientation and the sequence of signal changes, and reporting boundary crossing events.

[0058] Data transmission module 3 includes an Ethernet switch, a fiber optic transceiver, and wireless access point (AP) network equipment. All readers connect to the hospital's internal LAN via Cat 6 Ethernet cables or Wi-Fi, transmitting the collected tag data to the positioning server in the central computer room in real time.

[0059] The positioning server module 4 uses a high-performance server (CPU i7 or higher, memory ≥16GB, hard disk ≥1TB) running Windows Server or Linux operating system. The software deploys MySQL or an equivalent relational database to store wheelchair tag information, reader / writer device information, real-time location records, and historical trajectories. The core algorithm engine includes a status management module, a composite positioning module, and a trajectory analysis module, responsible for data processing, location calculation, status determination, and event triggering.

[0060] The monitoring terminal module 5 is distributed across nurse station 5-1, PC workstation 5-2, and mobile terminal 5-3. The software is a web-based monitoring platform that loads a tiered electronic map of the hospital (supporting outpatient floors 1-4 above ground and inpatient floors 1-13), displaying the icons, locations, and statuses (standby / in use / out of bounds) of all wheelchairs in real time. It supports clicking to query detailed information, replaying historical trajectories, and displaying alarm pop-up notifications.

[0061] The system's working principle and process include the following steps:

[0062] Step S1, System Initialization:

[0063] Enter the tag ID, asset number, deployment date, and other information of all wheelchairs into the positioning server to establish a one-to-one correspondence; deploy readers and configure the network, and associate the device ID of each reader with its deployment location (floor, area); establish a hierarchical electronic map of the hospital, and build an RSSI-based fingerprint positioning database on the server (optional).

[0064] Step S2, wheelchair loan detection:

[0065] When a patient pushes their wheelchair directly from the parking area, the parking area monitoring reader detects that the wheelchair tag signal changes from strong to weak until it disappears. The reader uploads the "signal disappearance" event (including tag ID, reader ID, and timestamp) to the positioning server through the data transmission module. The status management module in the positioning server updates the wheelchair status from "standby" to "in use" and records the retrieval time and retrieval area.

[0066] Step S3, In-hospital mobile positioning:

[0067] As the wheelchair moves within the hospital, the area positioning readers on each floor periodically read the tag, obtain the tag ID, RSSI value, and timestamp, and upload them. The positioning server estimates the current floor and approximate area of ​​the wheelchair (e.g., "Outpatient Building 2, East Corridor") based on the reader ID and RSSI value of the same tag data received, combined with pre-stored area information (or fingerprint database). The monitoring terminal module updates the wheelchair's icon position on the electronic map in real time and displays its current status.

[0068] Step S4, Floor Jump Detection:

[0069] When a wheelchair enters an elevator or passes through an escalator, the area positioning reader in the elevator lobby reads the tag. If the same wheelchair tag is captured by readers on different floors within a short period of time (e.g., 10-60 seconds), it is determined that a floor transfer has occurred. The positioning server updates the floor attribute of the wheelchair, and the monitoring map automatically switches to the corresponding floor and displays the wheelchair's location.

[0070] Step S5, Wheelchair Return Inspection:

[0071] When a wheelchair is pushed back to any parking area (which can be the original location or other designated parking spots), the parking area monitoring reader detects the reappearance and stable presence of the wheelchair tag signal. If the signal remains stable for more than a preset static threshold T (e.g., 5 minutes), it is determined to be returned. The positioning server updates the wheelchair status to "standby", records the return time and return area, and the wheelchair icon on the monitoring terminal is restored to the standby status indicator.

[0072] Step S6, boundary crossing alarm:

[0073] When a wheelchair is pushed to the hospital entrance / exit, the directional antenna of the reader at the entrance / exit boundary captures the wheelchair tag. The system determines the direction of movement based on the antenna orientation and the sequence of signal changes: if it is "going out" (from inside the hospital to outside), a boundary crossing alarm is triggered. The positioning server generates a boundary crossing event and displays the wheelchair ID, exit location, and boundary crossing time in a pop-up window on the monitoring terminal. At the same time, it can link to the real-time footage of nearby cameras (if the system integrates video surveillance) to remind management personnel to handle the situation in a timely manner.

[0074] Step S7, Historical Trajectory Tracing:

[0075] The positioning server continuously records the real-time location and status changes of each wheelchair, forming historical trajectory data; the monitoring terminal supports querying historical movement paths by time period and by wheelchair ID, and replays them on an electronic map, facilitating post-event analysis and locating lost wheelchairs.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID, characterized in that, It includes a wheelchair identification tag module, a reader network module, a data transmission module, a positioning server, and a monitoring terminal module; The wheelchair identification tag module uses a passive UHF RFID anti-metal electronic tag, which has no built-in battery, has a unique EPC code, and is installed on the unshielded part of the wheelchair's metal frame. The reader network module includes a parking area monitoring reader, an area positioning reader, and an entrance / exit boundary reader, which respectively realize in-situ monitoring, area positioning, and entrance / exit electronic fence functions; The positioning server includes a database and status management, composite positioning, and trajectory analysis algorithms to realize wheelchair status recognition, location calculation, event triggering, and data storage; the data transmission module includes an Ethernet switch, a fiber optic transceiver, and a wireless AP; the reader network module connects to the hospital's intranet via Category 6 network cable / Wi-Fi, and data is uploaded to the positioning server in real time. The monitoring terminal module is based on the hospital's hierarchical electronic map, enabling real-time display of wheelchairs, status monitoring, alarm prompts, and trajectory playback.

2. The hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID according to claim 1, characterized in that, The parking area monitoring reader is a low-power near-field reader with a coverage radius of 1-2 meters, used to identify whether a wheelchair is in place or out of place; when the tag signal disappears when the wheelchair is pushed away, it is determined that the wheelchair has been borrowed; when the signal is stable and exceeds a threshold when the wheelchair is returned, it is determined that the wheelchair has been returned.

3. The hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID according to claim 1, characterized in that, The area positioning reader is a high-power far-field reader that enables area positioning within a floor and floor transition detection.

4. The hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID according to claim 1, characterized in that, The entrance and exit boundary reader uses a directional narrow beam antenna to form an electronic fence, determine the direction of wheelchair entry and exit, and trigger a boundary crossing alarm.

5. The hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID according to claim 1, characterized in that, The positioning server uses a region-channel composite positioning algorithm, combined with RSSI or fingerprint database.

6. A monitoring method corresponding to the hospital wheelchair intelligent positioning and monitoring system based on passive UHF RFID as described in any one of claims 1-5, characterized in that, It includes the following steps: A. System initialization, binding tags to wheelchairs, readers to locations; B. Wheelchair borrowing detection: The wheelchair is determined to be borrowed when the signal in the parking area disappears, and the status is set to "in use". C. In-hospital mobile positioning, area reader collects data, and calculates the floor and area location; D. Floor transition detection: Elevator lobby recognition enables floor transition detection; E. Wheelchair return detection: If the signal in the parking area is stable and exceeds the threshold, the wheelchair is determined to be returned and the status is set to standby. F. The entrance / exit identifies the direction of exit and triggers a boundary crossing alarm.

7. The intelligent positioning and monitoring method for hospital wheelchairs based on passive UHF RFID according to claim 6, characterized in that, In step A, the tag IDs, asset numbers, deployment dates, and other information of all wheelchairs are entered into the positioning server to establish a one-to-one correspondence; readers are deployed and the network is configured to associate the device IDs of each reader with their deployment locations to create a hierarchical electronic map of the hospital.

8. The intelligent positioning and monitoring method for hospital wheelchairs based on passive UHF RFID according to claim 6, characterized in that, In step B, when the patient pushes the wheelchair directly from the parking area, the parking area monitoring reader detects that the wheelchair tag signal changes from strong to weak until it disappears; the reader uploads the signal disappearance event to the positioning server through the data transmission module; the status management module in the positioning server updates the wheelchair status from standby to in use, and records the retrieval time and retrieval area.

9. The intelligent positioning and monitoring method for hospital wheelchairs based on passive UHF RFID according to claim 6, characterized in that, In step C, as the wheelchair moves within the hospital, the area positioning readers on each floor periodically read the tag, obtain the tag ID, RSSI value, and timestamp, and upload them. The positioning server estimates the current floor and approximate area of ​​the wheelchair based on the reader ID and RSSI value of the same tag data received, combined with pre-stored area information; The monitoring terminal module updates the position of the wheelchair icon on the electronic map in real time and displays its current status.

10. The intelligent positioning and monitoring method for hospital wheelchairs based on passive UHF RFID according to claim 6, characterized in that, In step D, when a wheelchair enters an elevator or escalates an escalator, the area positioning reader in the elevator lobby reads the tag. If the same wheelchair tag is captured by readers on different floors within a short period of time, a floor transfer is determined. The positioning server updates the wheelchair's floor attributes, and the monitoring map automatically switches to the corresponding floor and displays the wheelchair's location. In step E, when a wheelchair is pushed back to any parking area, the parking area monitoring reader detects the reappearance and stable presence of the wheelchair tag signal. If the signal remains stable for more than a preset static threshold T, it is determined to be returned. The positioning server updates the wheelchair's status to standby, records the return time and return area, and the wheelchair icon on the monitoring terminal is restored to the standby status indicator. In step F, when a wheelchair is pushed to the hospital entrance / exit, the directional antenna of the entrance / exit boundary reader captures the wheelchair tag. The system determines the direction of movement based on the antenna orientation and the sequence of signal changes. If the movement is outside, a boundary crossing alarm is triggered. The location server generates an out-of-bounds event, which displays the wheelchair ID, exit location, and out-of-bounds time in a pop-up window on the monitoring terminal. At the same time, it can link to real-time footage from nearby cameras to alert management personnel to handle the situation promptly.

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